Welcome to the Forum!
Ok, by the portion of the serial number you posted, this gun was shipped in 1962. As for the info on the extra cylinder,, most likely,,, BUT,, w/o more info we can't be sure.
The best way to get the proper info on how it was shipped would be to spend $10 with Ruger Records to let them research the gun. If you get that letter from Ruger, it'll list how the gun was shipped by the model info, such as; RSS5X,, with the "X" signifying the extra cylinder.